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Connecting Theory and Practice in Optoelectronics

High-power GaN-based laser with tunnel junction

tunnel junction laserThus far, the highest output power measured on GaN-based lasers is about 7W, as shown in the picture. [1] In comparison, some GaAs-based lasers emit more than 30W in continuous-wave operation at room temperature. A key reason for this difference is the inherently large p-side electrical resistance of GaN-based laser diodes. It leads to strong Joule heating which lowers the gain and boosts various loss mechanisms that eventually cause the typical power roll-off at high currents. [2]

In search for a possible remedy, we recently simulated the effect of a p/n tunnel junction that replaces most of the p-doped layers by highly conductive n-doped material. First results look quite promising. [2] As shown by the red lines in the picture, the bias is substantially reduced and the peak lasing power is close to 20W. This simulation assumes a negligible tunnel junction resistance which is not yet accomplished in practical devices. [3] However, the numerical proof of concept hopefully helps stimulate further research efforts into GaN-based tunnel junctions for application in LEDs and lasers.

[1] M. Kawaguchi et al., Proc. SPIE 9748 (2016) 974818
[2] J. Piprek, Compound Semicond. Mag. 23 (2017) no. 5, pp. 34-38
[3] B. P. Yonkee et al., Opt. Express 24 (2016) 256556

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One response to “High-power GaN-based laser with tunnel junction

  1. Joachim Piprek 2017-09-29 at 08:07

    More details are now published in Optical and Quantum Electronics: http://rdcu.be/v4nW

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